Bolster spring unit



Aug. 29, 1939,

C. J. HOLLAND BOLSTER SPRING UNIT Filed Nov. 11, 1936 15211077250 7 was Holland Patented Aug. 29, 1939 UNITED STATES PATET ()FFIQE BOLSTER SPRING UNIT Application November 11, 1936, Serial No. 110,222

9 Claims.

This invention relates tospring suspension devices and. more particularly to friction spring units.

One of the objects of the invention is the provision of a new and improved spring member or spring unit that is provided with novel means for frictionally resisting the compression of the unit.

Another object of the invention is the provision of a new andimproved friction spring unit having a novel arrangement of springs and friction mechanism whereby a unit of maximum capacity within a minimum space is provided.

A further object of the invention is the provision of a new and improved spring unit that is inexpensive to manufacture, easily assembled, composed of few moving parts, and that is efiicient in use and that is not likely to become broken or get out of order.

Other and further objects and advantages of the invention will appear from the following description, taken in connection with the accompanying drawing in which Fig. 1 is a side elevation of a railway truck with parts omitted and parts broken away;

Fig, 2 is a vertical section of one of the spring units;

Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a perspective view of the cap member or follower of one of the units; and

Fig. 5 is a perspective view of the friction shoes.

In the conventional spring assembly for supporting the bolster of railway cars, it is common practice to employ helical or free acting springs,

Under certain conditions as when flat wheels develop or the road bed becomes uneven, the assembly will, at predetermined speeds, develop a harmonic movement that tends to build up to an undesirable extent. The present invention seeks to remedy this difficulty by the provision of a spring unit having a frictional resistance to the vibration of a bolster that is supported by such assembly.

In the form of the construction selected to illustrate one embodiment of this invention, a frictional spring unit is employed. This unit is adapted to be substituted for one or more of the helical springs of the bolster supporting spring assembly.

The tendency, at the present time, in the movement of freight cars is to increase their speed and this increased speed causes shocks from track joints, and the like. Where the natural period of vibration of the springs synchronizes with these shocks, there results harmonic action of the springs, which frequently becomes so violent as to drive the springs solid, thereby resulting in more or less serious damage to the equipment. The present invention seeks to remedy this difficulty by introducing into each of the spring assemblies, one or more friction spring units that will dampen the vibration of the spring assembly by introducing frictional resistance to the compression and recoil thereof. This frictional resistance will not only prevent harmonic action of the assembly, but the spring construction may be such that the capacity of the assembly may be increased.

Referring now to the drawing, the reference character 10 designates a conventional truck for railway cars comprising the side frame H having the conventional bolster opening I2 through which one end of the bolster l3 extends. The bolster is supported by a spring assembly I4 which comprises a plurality of springs l5 and one or more spring units It. The spring assembly or spring nest engages beneath the bolster l3 and is supported on a spring plank I60 in the usual manner. Since the details of the truck construction and arrangement of springs constitute no part of the present invention, it is not thought necessary to further illustrate or describe the same.

Each spring unit, comprises, what for convenience of description will be termed, a lower base portion ll, Fig. 2, which comprises a base flange l8 and an upwardly extending friction post 19. The friction post l9 has an axial recess 2| in its upper portion. The post 19 may be a hollow construction with a partition 22 across its intermediate portion for forming the axial recess 2|. The post It may, if desired, be slightly tapered toward its upper end. The post i9 is. preferably, though not necessarily, circular in cross-section and its outer surface is adapted to be frictionally engaged by a plurality of friction shoes 23, 24.

In the form of the device selected to illustrate one embodiment of the invention, two shoes are. employed. The upper ends of these shoes are provided with outwardly extending flanges 25 and 26, the upper surfaces of which constitute angular or wedge faces 21 and 28. These surfaces are cylindrical and segments of cylinders arranged at an angle to each other and to the axis of the unit, and are adapted to engage corresponding cylindrical angularly arranged wedge faces 29 and 3! on a cap or follower plate 32. By forming the wedging faces 21, 28, 29 and 3| each as a segment of a cylinder, binding of the parts is prevented when the unit is compressed, Furthermore, it will be noted, that with this arrangement, the portions of the follower plate 3i; and iii, Fig. 4, between the wedging faces are considerably thickened, thereby reinforcing the strength of the plates at points of greatest stress, without distort-- ing the periphery of the plate. The cap or follower plate 32 has an axial depressed portion 33 forming a recess 34! for receiving the upper end of the bolt 35 and the nut 35. The bolt 35 extends through the bottom wall of the depressed portion 33 and also through the partition 22.

Suitable means are provided for releasing the wedging members when the unit is released. As shown, an inner spring 31 is employed for this purpose. This spring not only functions to release the wedging mechanism but also materially assists in supporting the load. This is considered an important feature of the invention because, in devices of this type, the question of space is an important one. For instance, the unit nuist be of such dimensions as to be capable of being substituted for one of the helical springs of the conventional spring assembly. Practically all space in the present i it is utilized. Further" morc, by providing positive release for the wedging members, the wedging angles may be made more acute thereby materially increasing the capacity of the unit, if desired. The inner spring 3? seats in the annular recess 2i of the post is and engages the cap member 32 at its upper end. The bolt 35 extends axially through this spring and is adapted to hold the parts in assembled relation and, if desired, the spring 37 may be placed under initial compression by adjusting the nut '56.

A helical spring 38 surrounds the post and shoes and seats on the base flange I8 at its lower end and engages beneath the flanges 25 and of the shoes 23 and 2 1, respectively, at its upper end.

In the operation of the device, when force is applied to the cap or follower plate 32, the is forced downwardly against the tension of both springs 3i and 38 and due to the cooperating wedging faces of the shoes and plate, the shoes 23 and 25 are forced inwardly against the post 19 thereby causing frictional resistance to the downward movement of the cap member. Since the wedging faces of the shoes extend radially outwardly a considerable distance beyond the faces of the shoes that engage the post, the shoes will be forced to move inwardly while remaining in parallel planes. This is considered an important feature of this invention because it insures uniform friction throughout the contacting faces of the shoes and post whereby the wear will be more uniformly distributed. When the compression is released, the inner spring 37 pushing upwardly on the cap member 32 will insure against sticking or locking of the friction elements in their compressed position. This is also considered an important feature of the invention be cause, by means of this arrangement, not only the angle of the wedging faces 2'? and 28 of the shoes may be varied to secure the desired frictional resistance between the shoes and. post 53, but the post i 9 may also be tapered as desired to increase or decrease the capacity of the unit. If the post i9 be tapered, the contacting faces of the shoes and post will continue to be segments of cylinders but the axes of such cylinders for each set of surfaces will be parallel and at an angle to the axis of the post in order to accommodate the taper on the post.

While in the construction shown, the inner spring 3! is employed, it is understood that this spring may be omitted, if, and. when desired, unless the wedging faces of the shoes and plate are at the angles of repose or beyond, in which event there could be no release after compression without the inner spring.

It is thought from the foregoing taken in connection with the accompanying drawing that the construction and operation of my device will be apparent to those skilled in the art, and that changes in size, shape, proportion and details of construction may be made without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A bolster supporting spring unit, comprising a base, a post extending upwardly from said base and integral therewith, a plurality of friction shoes frictionally engaging the outer surface of said post, the extreme upper ends of said shoes having wedging faces, a cap member having wedging faces engaging the wedging faces of said shoes, a spring inwardly of said shoes and terminating inwardly of the outer ends of said shoes, and a spring outwardly of and surrounding said shoes and seated on said base for resisting the compression of said unit.

2. In a spring unit for use in, a load support ing spring assembly for railway cars, an. upwardly extending friction post, friction shoes substantially as long as said post normally engaging substantially the entire circumference of the outer surface of said. post throughout a portion only of the length of the shoes and post so that when the unit is compressed increased areas of the shoes and post will be engaged, said post having an internal stiffening partition directly con.- necting its opposite sides, a cap member and coacting wedging surfaces on said cap member and shoes for forcing said shoes inwardly into frictional contact with said post when said unit is compressed, and resilient means including a spring surrounding said shoes and engaging the same for yieldingly resisting the compression of said unit.

3. A load supporting spring unit comprising, an upwardly extending friction post, friction shoes engaging substantially the entire outer surface of the inner end of said post, a cap member and coacting wedging surfaces on said cap member and the outer ends of said shoes for forcing said shoes inwardly into frictional contact with said post when said unit is compressed, said post having a recess in its upper portion, a spring seated within said recess and engaging said cap member, and a spring surrounding said shoes and reacting between said post and shoes for yieldingly resisting the relative movement of said post and shoes.

4. A spring unit for use in load supporting spring assemblies for railway cars, a hollow friction post having a partition, said post having a base flange, a plurality of friction shoes frictionally engaging substantially the entire surface of the outer end of said post, each shoe having an outwardly extending flange at the opposite end of said unit from said base flange and provided with a wedging face on its upper surface, a cap member having wedging faces engaging the wedging faces on said shoes, a spring between the flanges on said shoes and said base flange, and a spring within the upper end of said post, engaging said cap member and seated on said partition.

5. A spring unit comprising a friction post, friction shoes engaging said post, each shoe having an inner substantially semi-circular friction surface, a cap member having wedging faces in the form of segments of cylinders for forcing said shoes into frictional engagement with said post when said unit is compressed, a spring reacting directly on said cap member for releasing the wedging action of said faces, and a spring for returning the parts to normal position after release.

6. In combination, a friction post having a lower base flange, a plurality of shoes frictionally engaging substantially the entire outer surface of the inner end of said post, said shoes having flanges on their upper ends, said second named flanges having wedging faces on their outer surfaces, a follower plate having wedging faces for engaging the wedging faces of said shoes for forcing the latter into frictional engagement with said post throughout the length of said shoes, and resilient means surrounding said shoes and reacting between said base and shoes, flanges for restoring the parts to normal position after release.

7. In a spring unit, a post having a. plurality of friction surfaces, friction shoes engaging said surfaces, said shoes having shoulders and provided with wedging surfaces on their outer ends, said surfaces being segments of cylinders, a follower plate having inclined faces engaging said wedging faces, for forcing said shoes inwardly in parallel planes into frictional engagement with the friction surfaces of said post, and resilient means engaging said shoulders for restoring the parts tonormal position after release.

8. In a spring unit, a post having friction faces thereon, a pair of shoes frictionally engaging said faces, said shoes each being substantially semicircular in cross-section having radially extending flanges provided on. their outer surfaces with segmental cylindrical wedging faces and a follower plate having a pair of corresponding seg. mental cylindrical wedging faces engaging the wedging faces of said shoes for forcing said shoes inwardly in parallel planes against said post during the compression of said unit, and spring means for resisting the compression of said unit and for returning the parts. to normal position after release.

9. A spring unit for use in load supporting spring assemblies for railway cars comprising a hollow friction post having a partition therein spaced from its lower end and provided with a base flange on its lower end, a pair of shoes. engaging substantially the entire peripheral surface of the upper end of said post and, having an, outwardly extending flange at their upper ends, the upper surface of said flange having a cylindrical surface extending downwardly and outwardly, a massive cap member having a cylindrical wedging face at opposite sides. thereof for engaging the upper faces. of said shoes, said cap having a depressed central portion, a spring seated on said partition and engaging said depressed portion, a bolt extending through said partition axially along said unit and cap, and a spring surrounding said shoes and seated on said base flange and bearing at its upper end against the flanges of said shoes.

CYRUS J. HOLLAND. 

